Method of hose manufacture

ABSTRACT

A flexible, stretchable, crush resistant hose particularly well suited for supplying breathing gases to patients in medical applications and the like is formed by providing a helix of coils of thermoplastic material that are bonded to a web of thermoplastic material, preferably along inner diameter surface portions of the coils. The web extends radially outwardly from between adjacent coils to define a helical reverse-direction crease at a maximum outer diameter of the hose when the hose is in a normal minimal-length condition wherein the coils are situated side-by-side sandwiching portions of the web therebetween. The thermoplastic material of hose is stress relieved by an annealing process performed while the hose is axially compressed after the hose is formed.

CROSS-REFERENCE TO RELATED PARENT APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/799,263 entitled FLEXIBLE, STRETCHABLE, CRUSH RESISTANT HOSE WELLSUITED FOR MEDICAL APPLICATIONS, filed Apr. 21, 2010 by Martin E.Forrester and Ralf Jourdan, which was filed as a continuation-in-part ofU.S. patent application Ser. No. 12/354,291 entitled STRETCH HOSE filedJan. 15, 2009 by Ralf Jourdan, which claimed the benefit of U.S.provisional application Ser. No. 61/335,023 entitled FLEXIBLE HOSE FORMEDICAL APPLICATIONS filed Dec. 30, 2009 by Martin E. Forrester

The disclosures of all of the applications referenced above areincorporated herein by reference.

The present invention relates to method of forming a flexible andeasy-to-stretch hose that is crush resistant and well suited to providea constant supply of air, anesthesia gas or gas-carried medication to aface mask, nasal mask or tracheotomy tube for a variety of purposes suchas anesthesia, life support or medication delivery, or to help preventsleep apnea.

Because this application is a continuation of a “parent application,”the specification of the parent application is presented just below,without any addition of “new matter.”

BACKGROUND

The present invention relates to a flexible and easy-to-stretch hosethat is crush resistant and well suited to provide a constant supply ofair, anesthesia gas or gas-carried medication to a patient's face mask,nasal mask or tracheotomy tube for a variety of purposes such asanesthesia, life support or medication delivery, or to help preventsleep apnea. Flexible, stretchable, crush resistant hoses embodyingfeatures of the invention are also well suited to evacuate gaseouspollutants from surgical areas, such as the removal of smoke duringlaser surgery.

Some prior crush resistant plastic hose proposals call for the use ofsolvents or glues to bond a web of thin material to coils of a helixthat cooperate with the web to give the resulting hose its crushresistance. However, the use of solvents in the manufacture of crushresistant hoses is undesirable in medical applications because theresulting hoses may bring the patient into contact with trace amounts ofthe manufacturing solvent or glue, or the solvent or glue may reactundesirably with medication being administered through the hose to apatient.

Some prior crush resistant plastic hose proposals intended for medicaluse are produced by extruding a thin web of plastic material to providea connecting wall extending between adjacent coils of a helix ofplastic. This connecting web may take a wavey form or may incorporateaccordion-like folds that enable the hose to extend and contract in anaccordion-like manner to give the resulting hose a measure offlexibility.

Although the hoses that result from the process just described may beeffective in delivering air or gas-borne substances to the patient, thenature of the extrusion process used to produce these hose productstypically causes the resulting hoses to exhibit a high degree oftorsional stiffness and a diminished degree of flexibility due to theorientation of the molecules that form not only the thin wavy wall butalso the helix that enhances the crush resistance of the hose. Thetorsional stiffness can cause a patient's face mask or nasal mask tolift off the face during movements of the patient's head, therebyallowing unwanted ambient air to enter the breathing circuit duringtherapy. The stiff nature of existing products also may causeundesirable stress on a tracheotomy tube during patient movement, andcan render difficult head movements of a patient.

DESCRIPTION OF THE DRAWINGS A fuller understanding of the invention maybe had by referring to the following description, taken in conjunctionwith the accompanying drawings, wherein:

FIG. 1 is a perspective view showing a length of flexible, stretchable,crush resistant hose embodying features of the present invention, withthe hose in its normally fully contracted condition wherein radiallyoutwardly extending portions of a thin, extruded web of plastic materialthat extends between coils of a crush resistant plastic helix of thehose are snugly sandwiched between adjacent side-by-side coils of thehelix;

FIG. 2 is a side elevational view of the hose length, with the flexiblehose in its normally fully contracted condition;

FIG. 3 is a right end view of the hose length;

FIG. 4 is a cross-sectional view, on an enlarged scale, as seen from aplane indicated by a line 4-4 in FIG. 3, showing a portion of the lengthof flexible hose in a slightly less than fully contracted condition,with a left portion of the view illustrating how the thin, extruded webof plastic material has its opposite edge regions extending inside flatinterior surfaces defined by the coils of the helix just prior to whenthe edge regions are welded by an application of heat energy to the flatinterior surfaces of the. coils of the helix, and with a right portionof the view showing how the cross-section changes once the welding orbonding of the web edge regions to the coils of the helix has takenplace, causing the thin, extruded web and the coils of the helix to forman integral hose product; and,

FIG. 5 is a cross-sectional view similar to FIG. 4 but showing a portionof the length of flexible hose product in an axially extended condition.

DETAILED DESCRIPTION

Referring to FIGS. 1-3, a length of flexible, stretchable, crushresistant hose embodying features of the present invention is indicatedgenerally by the numeral 100. The hose 100 has coils 110 of a relativelystiff plastic material that form a helix 120, and has a thin web or wall130 of plastic material that extends between the coils 110 of the helix120.

Although the hose 100 can undoubtedly be formed in a variety of ways, apreferred manufacturing technique employed during manufacture calls forthe materials that form the coils 110 of the helix 120 and the thin webor wall 130 to be extruded, either concurrently as separate extrusionsof the helical coils 110 and the thin web or wall 130 that are promptlybonded or welded together while still hot following extrusion, or as asingle extrusion that forms the helical coils 110 together with anintegral reach of thin web or wall 130 that also is welded or bondedpromptly while still hot to form the hose 100.

What is referred to by use herein of the terms “welded,” “bonded,”“welding” and “bonding” is a joining together, in a heated environmentor as a result of an application of heat energy (whether applied byradiation, convection, the use of laser-generated light or any otherknown or yet to be developed technique, or a combination thereof) ofthermoplastic materials from which components of the hose 100 may beformed, including but not limited to PVC, TPU, PP, TPE, ABS and otherthermoplastic materials and reasonable equivalents thereof, to form whatresults in or amounts to an integral assembly that typically exhibits noremaining borders between adjacent portions of the bonded or weldedmaterials. In essence, the terms “welded” and “bonded,” and the terms“welding” and “bonding” are used interchangeably, with no differences ofmeaning intended therebetween.

As depicted in FIGS. 1 and 2, the flexible, stretchable, crush-resistanthose 100 is in its normally fully contracted condition (also referred toherein as its “normal condition”), with the coils 110 of the helix 120situated side-by-side relatively snugly sandwiching radially outwardlyextending portions 152 (FIG. 4) of the thin plastic web or wall 130therebetween. The hose 100 has its minimal length when it is in itsnormal condition as depicted in FIGS. 1 and 2, and can be stretched orextended, for example as is shown in FIG. 5, which causes the coils 110of the helix 120 to separate, and causes the outwardly extendingportions 152 of the thin web or wall 130 to flatten out or “unfold,”typically in the manner depicted in FIG. 5. If, during stretching orextension, the hose 100 is caused to bend or deflect (from any of thelinear or straight-line configurations that are depicted in FIGS. 1, 2,4 and 5), the crush resistant character of the hose 100 will permit thebending or deflection to take place without significantly diminishingthe inner diameter (designated by the numeral 140 in FIG. 3) of the hose100.

The coils 110 of plastic material that form the helix 120 have a uniformcross-section that preferably features a rounded exterior surface 112and a substantially flat interior surface 114. When the substantiallyflat interior surface 114 is viewed from an end of the length of hose100, as is depicted in FIG. 3, it will be seen to take the form of acircle which defines the interior diameter 140 of the hose 100. Thesecircles defined by all of the coils 110 are substantially the samediameter.

Referring to the left “half” of FIG. 4, the thin web or wall 130 thatextends between adjacent pairs of the coils 110 is preferably formed byextruding a thin, flat, elongate, tape-like or band-like web of plasticmaterial 132 that ultimately has its opposite edge regions 134 bonded orwelded to the flat interior surfaces 114 of the coils 110. As is shownsomewhat schematically in the left “half” of FIG. 4, the edge regions134 of the thin wall or web 130 each preferably extend about halfwayinto and along the flat interior surfaces 114 of the coils 110 -- atwhich locations the edge regions 134 are welded or bonded to the flatsurfaces 114 by an application of heat energy to form an integral hose100, in a manner that is depicted in the right “half” of FIG. 4.

In essence, such boundaries as exist between the edge regions 134 andthe flat interior surfaces 114 (as depicted in the left “half” of FIG. 4at a time before welding or bonding takes place) effectively “disappear”as the thermoplastic .materials forming the coils 110 and the web edgeregions 134 merge and integrally bond during welding or bonding to formthe integral hose product 100 that is shown in the right “half” of FIG.4.

If identical thermoplastic materials are used to form the coils 110 ofthe helix 120 and the thin web or wall 130, the hose 100 that resultswhen a proper thermoplastic welding or bonding process has beencompleted is a one-piece member with no discernible borders orboundaries.

If, on the other hand, different thermoplastic materials (for example amaterial used to form the coils 110 of the helix 120 that has a highermodulus of elasticity than does a material used to form the thin web orwall 130) are separately extruded and properly thermoplastically weldedor bonded to form the hose 100, the material of the web or wall 130 mayprovide a contiguous, continuous and uninterrupted liner that shieldsthe material of the coils 110 of the helix 120 from contact with gasesand the like that flow through the inner diameter 140 of the hose 100 --which, in certain medical applications may be of importance to preventinteractions between the material forming the coils 110 of the helix 120and certain medications being carried by gases flowing through the hose100.

To enhance the stretchability and flexibility of the hose 100 withoutdiminishing its crush resistance, and to thereby avoid the problems ofstiffness that are characteristic in many of the crush resistant hosesof prior proposals, the bonded or welded hose product 100 is subjectedto an annealing process that modifies the orientation of the moleculesof thermoplastic that forms the coils 110 of the helix 120 and the thinwall or web 130 that extends between the coils 110 of the helix 120.

When the hose 100 initially is formed, the coils 110 of the helix 120are relatively widely spaced, and the thin web of plastic material thatextends between adjacent pairs of the coils 110 takes a cylindricalshape that does not project radially outwardly at locations between thecoils 110 of the helix 120. However, as the annealing process is carriedout, the coils 110 of the helix 120 are moved closer and closer towardeach other, which causes the web 130 situated between adjacent pairs ofthe coils 110 to bulge radially outwardly, creating the radiallyoutwardly extending portions 152. As the elements of the hose 100 cometo the “normal condition” depicted in FIGS. 1 and 2) wherein the coils110 assume side-by-side positions snugly sandwiching the radiallyoutwardly bulging web 130 therebetween, a reverse-direction crease orfold 150 (see FIGS. 4 and 5) is caused to form and set at a centrallocation extending along the length of the tape-like or band-like web orwall 130.

As the heating and controlled cooling of the annealing process iscompleted with the hose 100 in its minimal-length “normal condition” (asdepicted in FIGS. 1 and 2), the molecules of the material of the coils110 and the web or wall 130 relax and take on a new orientation with amemory of the “normal condition” to which the completed hose 100 willnormally return when released from the imposition of external forces(including the force of gravity). And, because stress is substantiallyabsent from the hose 100 when the coils 110 of the hose 100 areside-by-side compressing the radially extending web or wall portions 152therebetween (i.e., when the hose 100 is in its “normal condition” asdepicted in FIGS. 1 and 2), the hose 100 begins resisting extension onlywhen, and to the extent that, the hose 100 is stretched causing it tolengthen.

Stated in another way, the annealing process to which the hose 100 issubjected allows the hose 100 to exhibit a greater degree of flexibilityand an ease of being stretched than are exhibited by conventional,non-annealed hose products, and enables the hose 100 to, in effect,provide a “strain relief” between medical delivery equipment (not shown)that typically is connected to one end region of a length of the hose100, and a patient's facial or nasal mask (not shown) that typically isconnected to an opposite end region of the same length of hose 100 inmedical applications that often make use of the hose 100.

Yet another benefit of the annealed and stress-relieved hose 100 (whichresults from stresses that were introduced during the manufacture of thehose 100 being relieved during annealing) is that the stress-relievedhose 100 does not take a set (i.e., does not take on a configurationalmemory to which the hose 100 seeks to return) when deflected or bent inany one direction or orientation for a lengthy period of time.

When the hose 100 is in its normally fully contracted condition, as isdepicted in FIGS. 1 and 2, the centrally located reverse-directioncrease or fold 150 that is set in the thin tape-like or band-like web orwall 130 is located radially outwardly beyond the rounded exteriorsurfaces 112 of the coils 110 that form the helix 120 (a feature bestseen in FIG. 4). The length of the radially outwardly extending portions152 of the web 130 (that extend from the inner diameter 140 of the hose100 to the reverse-direction creases or folds 150 that define the outerdiameter of the hose 100) provides the web or wall 130 with a greatersurface area to displace during flexure of the hose 100 (than typicallyis found in present day hoses utilized to deliver air, medicinal gasesand the like in today's medical environments) -- which also helps toenhance the flexibility of the hose 100.

A feature of the hose 100 is its extensibility (i.e., the ease withwhich the hose 100 can be stretched). The length of the radiallyoutwardly extending portions 152 of the web 130, and the accordion-likereverse-direction crease or fold 150 that extends radially outwardly ofthe curved outer surfaces 112 of the coils 110 of the helix 120 givesthe hose 100 an impressive ability to extend when a patient situatednear one end of a reach of the hose 100 moves relative to a medicalapparatus connected to an opposite end of the reach of hose 100 -- whichis to say that the hose 100 provides a “strain relief” that minimizesthe transmission of force along the length of the hose 100.

What a length of the hose 100 typically offers is an ability to stretch(in an example manner depicted in FIG. 5) to a length of at least aboutone and a half times the length that is exhibited by the hose when atrest in a normally fully contracted condition (as is depicted in FIGS. 1and 2). This extensibility characteristic represents a significantimprovement in comparison with such limited extensibility as may beoffered by many present day crush resistant hoses that are beingutilized to deliver gases in medical applications.

When the hose 100 is extended in the manner depicted in FIG. 5, thememory of the hose 100 provides a gentle spring effect that will tend toreturn the hose 100 to its normal fully contracted condition (i.e., its“normal condition” as depicted in FIGS. 1 and 2) when the force causingthe hose to extend diminishes and is relieved. This gentle spring effectis unlike the forceful resistance to stretching or extension that oftenis encountered with the use of present-day crush resistant hoses in useto deliver gases in medical applications.

When the hose 100 is extended (for example, in the manner depicted inFIG. 5), the radially extending portions 152 and the reverse-directioncreases or folds 150 of the web or wall 130 are pulled radially inwardly-- but not in a way that diminishes the interior diameter 140 (labeledin FIG. 3) of the hose 100 that exists after the web 130 and the coils110 of the helix 120 are bonded or welded to form the integral hoseproduct that is depicted in the right “half” of FIG. 4 wherein the edgeregions 134 shown in the left “half” of FIG. 4 (at a time prior tobonding or welding) have become integrally bonded or welded to the coils110 of the helix 120.

In one preferred embodiment of the hose 100, the spring tension thattends to cause the hose to retract to the normal condition builds up inthe hose only when the hose is stretched, and the spring tensionattributable to the thermoplastic material forming the web in proportionto the spring tension attributable to the thermoplastic material formingthe coils of the support spiral is at least about 25% to at least about50%; and, in some embodiments, this ratio may be at least about 25% toas high as at least about 90%.

In one preferred embodiment of the hose 100, the helix 120 and the web130 are formed from the same thermoplastic copolyester elastomer, alsoknown as TPC-ET. One suitable example of a TPC-ET material well suitedto form the hose 100 is sold by E.I. Dupont deNemours & Company underthe registered trademark HYTREL -- the torsional stiffness of which canbe relieved by heating the welded hose 100 during an annealing process.The stress relieved hose 100 that results once the annealing process iscompleted is of continuously wound, heat welded, thermoplasticconstruction, and uses no solvents or glues to bond or weld the plastichelix 120 to the edge regions 134 of the thin web or wall 130 atlocations along the flat inner surfaces 114 of the coils 110 of thehelix 120.

Hoses 100 embodying such features as are described herein can beproduced in sizes a small as 0.315 inch inside diameter, making the hose100 ideal for medical applications where lightweight, small diameterhoses are needed.

An objective of the annealing process to which the hose 100 is subjectedis to diminish torsional stiffness of the resulting hose. Torsionalstiffness is defined as how much twisting force is transmitted throughthe hose 100 before it “breaks away” into an arc or spiral that willabsorb additional twisting force when one end is held securely to afixed point. This could also be regarded as the “twisting yield point.”

For example, when a nurse moves a piece of life support equipmentconnected to a patient with a hose of high torsional stiffness, a greatdeal of the movement is transmitted through the hose to the patientinterface, which creates a potential for the interface to leak or becomedisconnected from the patient. However, a hose with low torsionalstiffness used in the same situation will “break away” into an arc orspiral thereby reducing the force that is transmitted to the patientinterface, which is less likely to cause a face mask or the like to bemoved from properly engaging the face of a patient.

The torsional stiffness of a hose can be determined quantitatively bymeasuring the amount of force required to cause a length of the hose ofapproximately five to ten times the internal diameter of the hose to“break away” from alignment with an axis that extends centrally throughthe hose, with one end of the hose under test being connected to atorque measuring device, and with the other end being turned in adirection opposite that of the wind of the helix of the hose. Theannealing process to which the hose 100 is subjected typicallydiminishes torsional stiffness by at least about 20 percent whencompared with similar hoses presently in use in medical applications.

A hose 100 embodying features of the present invention can be formedusing a two step manufacturing process. A first step is to continuouslywind a molten plastic (preferably a thermoplastic copolyester elastomer)profile in the shape of both the thin wall 130 and the helix 120portions of the hose 100 around a series of spinning mandrels that areangled to allow the profile to progress forwardly off of the mandrels.The angle is controlled to insure there is a sufficient bond of the edgeregions 134 of tape-like thin wall 130 to the flat inside surfaces 114of the coils 110 of the helix 120. The angle provides the necessarypitch of helix spacing, which is typically two to five times the finaldimension of the resulting hose 100 after annealing.

A second step is to anneal the hose 100. This may be achieved bycompressing the hose 100 axially, and placing the hose 100 in an oven ata temperature below the melting temperature of the plastic material thatforms the hose 100, for enough time 1) to relieve such stress as wasintroduced during the extrusion process, and 2) to cause the fold 150 tobe set into the thin wall 130 of the hose 100. The hose 100 is thenremoved from the oven, whereafter the hose 100 is cooled and flexed toensure that the desired degree of flexibility has been achieved.

Although a thermoplastic copolyester elastomer (TPC-ET) material such asDupont HYTREL is a preferred material from which to form all componentsof the hose 100, the helix 120 and the web 130 components of the hose100 may be formed from different thermoplastic materials, or fromthermoplastic materials that differ from TPC-ET. Either or both of thehelix 120 and the web 130 that connects adjacent coils 110 of the helix120 may, for example, be formed from PVC, TPU, PP, TPE or ABSthermoplastic, or from any other commercially available thermoplasticpolymers or blends thereof.

When the same TPC-ET material is used to form both the helix 120 and theweb 130, the helix 120 and the web 130 can be extruded from a singledie. TPC-ET is desirable for use in forming the hose 100 when the hose100 is to be used in medical applications because the TPC-ET can besteam autoclaved to sterilize the hose 100, as is desirable in medicalenvironments.

TPC-ET material is naturally clear or translucent in thincross-sections, such as are employed in forming the web 130 of the hose100, and becomes opaque in thicker sections such as are employed informing the helix 120. Thus, even though the same TPC-ET material may beused to form the web 130 and the helix 120 of the hose 100, theresulting hose 100 will likely have the appearance of being formed fromtwo different materials.

Alternatively, the hose 100 may be formed from two different materialsin order to create a totally transparent hose, or to create a two colorhose, or a clear walled hose that has a specific colored helix -- whichmay be desirable in order to “color code” particular reaches of the hose100 so they will be consistently used to deliver only particular gasesor gaseous mixtures to patients. Colorants can, of course, be added toany of the plastic materials used to form the hose 100 to achievepractically any desired color combination.

Materials having different characteristics such as a different hardnesscan be used to form the web or wall 130 and the coils 110 of the helix120, which may involve the use of two separate extruders and either aco-extrusion die, or separate dies to create the web 130 and helix 120separately, whereafter they are welded or bonded. Likewise, materialsthat have different moduli of elasticity may be used to form the web orwall 130 and the coils 110 of the helix 120 -- with, for example, thematerial forming the coils 110 of the helix 120 having a higher modulusof elasticity than the material forming the web or wall 130, to enhancethe crush resistance of the resulting hose 100.

Although the invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made only by way of example,and that numerous changes in the details of construction and the mannerof manufacture may be resorted to without departing from the spirit andscope of the invention. It is intended to protect whatever features ofpatentable novelty exist in the invention disclosed.

The claims that follow are intended to protect whatever features ofpatentability that exist in the invention features disclosed in thetext, the drawings and the claims hereof and in the referencedprovisional and parent applications, the disclosures of which areincorporated herein by reference.

What is claimed is:
 1. A method of forming a flexible, stretchable,crush resistant axially extending hose, comprising the steps ofproviding coils entirely of thermoplastic material to form a continuoushelix of substantially constant diameter, providing a thin, narrow,elongate web of thermoplastic material that extends between adjacentcoils of the helix and has edge regions welded to adjacent ones of thecoils to form a single continuous wall with the web having a radiallyoutwardly extending, centrally located fold situated between adjacentones of the coils, and enhancing the flexibility of the hose bysubjecting the hose to an annealing process while axially compressingthe hose so that molecules of the thermoplastic material forming thecoils of the helix and the thin elongate web are relaxed such thatstress is substantially absent from the hose when the coils of the helixare close together.
 2. The method of claim 1 wherein the annealingprocess is completed while the hose is axially compressed to a minimallength normal condition wherein the coils of the helix are side-by-sidesnugly sandwiching radially outwardly extending portions of the webtherebetween to give the resulting hose a memory of the normal conditionto which the hose will tend to return when released from external forceinfluences.
 3. The method of claim 1 wherein the coils of the helix areformed to have a substantially uniform cross-section with a curved outersurface and a substantially flat inner surface that defines an interiordiameter of the hose.
 4. The method of claim 2 wherein the hose isformed such that, when the hose is in the normal condition, portions ofthe web that extend radially outwardly define a reverse-direction creaseat a maximum outer diameter of the hose.
 5. The method of claim 4additionally including the step of utilizing the annealing process toset the reverse-direction crease.
 6. The method of claim 1 additionallyincluding the steps of forming the coils of the helix with asubstantially uniform cross-section, and forming the material of the webto have a substantially uniform thickness.
 7. The method of claim 1wherein the step of providing thermoplastic material to form the helixand the step of providing thermoplastic material to form the web includeproviding the same thermoplastic material.
 8. The method of claim 1wherein the step of providing the thermoplastic material to form thehelix includes providing thermoplastic material selected from among PVC,TPU, PP, TPE and ABS thermoplastic, and the step of providingthermoplastic material to form the web includes providing thermoplasticmaterial selected from among PVC, TPU, PP, TPE and ABS thermoplastic. 9.The method of claim 2 wherein the hose is provided with spring tensiontending to cause the hose to retract to the normal condition that buildsup in the hose only when the hose is stretched, with the spring tensionbeing attributable to the thermoplastic material forming the web inproportion to the spring tension attributable to the thermoplasticmaterial forming the coils of the support spiral being at least about25% to at least about 50%.
 10. The method of claim 1 wherein differentthermoplastic materials are used to form the helix and the web, with thethermoplastic material forming the helix being selected to have a highermodulus of elasticity than that of the thermoplastic material formingthe web.
 11. The method of claim 2 wherein the thermoplastic materialsselected to form the hose provide a stretch ratio of the length to whichthe hose can be stretched in comparison to the length of the hose in thenormal condition that is at least 1.5:1.
 12. The method of claim 1wherein the thermoplastic materials selected to form the hose provide aspring constant effective when the hose is stretched that has a value of5 N/m to 25 N/m, with these values being determined by the thickness ofthe web and the nature of the material selected to form the web.
 13. Amethod of forming a flexible, stretchable, crush resistant, axiallyextending hose for supplying gases to patients in medical applications,comprising the steps of providing coils entirely of thermoplasticmaterial that form a substantially uniform diameter helix, providing athin web of thermoplastic material bonded to adjacent coils of the helixalong inner diameter portions of the coils to form a single continuouswall and extending radially outwardly from between the adjacent coils toform a helical reverse-direction crease that defines a maximum outerdiameter of the hose when the hose is in a normal condition wherein thecoils are situated as closely together as possible, snugly sandwichingthe material of the web therebetween, and subjecting the resulting hoseto an annealing process to enhance the flexibility of the hose and tominimize the force needed to stretch the hose by axially compressing thehose during the annealing process so that molecules of the thermoplasticmaterial forming the helical coils and forming the web are relaxed suchthat stress is substantially absent from the hose when the coils of thehelix are closer together.
 14. The method of claim 13 wherein theannealing process is completed while the hose is axially compressed to aminimal length normal condition wherein the coils of the helix areside-by-side snugly sandwiching radially outwardly extending portions ofthe web therebetween to thereby give the resulting hose a memory of thenormal condition to which the hose will tend to return when releasedfrom external force influences.
 15. The method of claim 13 wherein thecoils of the helix are formed to have a substantially uniformcross-section with a curved outer surface and a substantially flat innersurface that defines an interior diameter of the resulting hose.
 16. Themethod of claim 13 wherein the annealing process that is provided duringaxial compression of the hose is performed such that, in the normalcondition, portions of the web that extend radially outwardly define areverse-direction crease at a maximum outer diameter of the hose. 17.The method of claim 16 wherein the reverse-direction crease is setduring the annealing process.
 18. The method of claim 13 wherein thecoils of the helix are formed to have a substantially uniformcross-section, and the material of the web is formed to have asubstantially uniform thickness.
 19. The method of claim 13 whereindifferent thermoplastic materials are used to form the helix and theweb.
 20. The method of claim 13 wherein the same thermoplastic materialsare used to form the helix and the web.
 21. The method of claim 13wherein the thermoplastic material selected to form the helix isselected from among PVC, TPU, PP, TPE and ABS thermoplastic, and thethermoplastic material selected to form the web is selected from amongPVC, TPU, PP, TPE and ABS thermoplastic.
 22. The method of claim 13wherein thermoplastic material is selected to provide the hose with aspring tension that tends to cause the hose to retract to the normalcondition that builds up in the hose only when the hose is stretched,and said spring tension attributable to the thermoplastic materialforming the web in proportion to the spring tension attributable to thethermoplastic material forming the coils of the support spiral is atleast about 25% to at least about 50%.
 23. The method of claim 13wherein the thermoplastic material selected to form the helix has ahigher modulus of elasticity than the thermoplastic material selected toform the web.
 24. The method of claim 13 wherein thermoplastic materialselected to form the hose provides the hose with a stretch ratio of thelength to which the hose can be stretched in comparison to the length ofthe hose in the normal condition of at least 1.5:1.
 25. The method ofclaim 13 wherein thermoplastic material selected to form the hoseprovides the hose with a spring constant effective when the hose isstretched having a value of 5 N/m to 25 N/m, with these values beingdetermined by the thickness of the web and the nature of the materialselected to form the web.